1. Field of the Invention
Embodiments of the present invention generally relate to network communications. More particularly, the present invention relates to a method and apparatus for WiFi long range radio coordination.
2. Description of the Related Art
Humans communicate with each other using various networking technologies. 802.11 represents a set of wireless networking standards that was promulgated by the Institute of Electrical and Electronics Engineers (IEEE). The 802.11 family (i.e., 802.11 legacy, 802.11g, 802.11n, and the like) includes multiple over-the-air modulation techniques that all use the same basic protocol. The 802.11 family facilitates the transmission and reception of data between two or more computers (e.g., servers, laptops, and the like), networking devices (e.g., adapters, gateways, routers, access points, and the like) and/or mobile devices (e.g., Bluetooth devices, Personal Desktop Assistants, mobile phones, and the like). WiFi is used to describe a networking interface of a mobile computing device that is coupled to a wireless local area network built on 802.11.
The wireless local area network may also include an access point between the mobile computing device and higher tiers of the network (e.g., a gateway, a backhaul device, a backbone network, and the like). The access point may use a radio connected with an antenna to communicate with computers, mobile devices, and/or other access points at short distances. The antenna may be omnidirectional (i.e., an antenna system which radiates power uniformly in one plane with a directive pattern shape in a perpendicular plane) or directional (i.e., an antenna which radiates greater power in one or more directions allowing for increased performance on transmit and receive and reduced interference from unwanted sources). Due to the deficiencies of the omnidirectional antenna, any access point using the antenna has a limited coverage area. An access point using one or more directional antennas may require multiple radios to achieve 360° of coverage.
Multiple radios, however, can cause interferences between the radios as they attempt to transmit and receive data at the same time. Interferences may occur despite the fact that the radios operate at different frequencies. An access point using multiple radios typically lacks adequate adjacent and/or alternate channel rejection and sufficient physical isolation and filtering between the radios. Due to the fact that there are only three non-overlapping channels in the 2.4 GHz ISM band that supports an 802.11 protocol signal, multiple radios capable of adequate adjacent channel rejection would still be unable to achieve a sufficient increase in antenna gain.
A typical access point for a WiFi-enabled network, for example, transmits at or around 17 dBM, which may be increased in certain cases to 30 dBm. Receptions at lower modulations (i.e., longer range links) typically occur down to −90 dBm. Therefore, up to 120 dB of isolation may be needed between the antenna sectors to permit simultaneous signal reception and transmission. Adjacent channel rejection from a number of chips may produce 30 dB, and the sectors may have 50 dB of physical isolation. As a result, 40 dBm of interference may exist between adjacent channels/sectors.
Hence, there is a need for a method and apparatus for coordinating WiFi long range radios. This is particular important for asynchronous 802.11 technologies because multiple radios enable signal reception at any of the antennas given the fact that 802.11 stations can transmit at any time and cause simultaneous signal transmission and reception at a given node.